RADIATION-STIMULATED DIFFUSION IN PLASMA-ION DEPOSITION OF COATINGS

Abstract

The diffusion of defects in a carbon coating when its surface is bombarded with heavy low-energy ions is theoretically studied, taking into account a sharp increase in the rate of kinetic processes in nonlocal thermoelastic peaks (NTPs) of ions, i.e., in superheated nanometer regions that arise around ion trajectories in the target material. The thermal energy density in NTP is comparable to or exceeds the activation energies of many physical and chemical processes, as a result of which their contribution to the total diffusion of defects in the near-surface layer of the target can be significant. Based on the NTP model, expressions were obtained for the average diffusion coefficient in the near-surface layer of the target, controlled by a beam of incident ions, as well as for the diffusion acceleration index. The dependences of the diffusion acceleration index on the ion energy are presented for various species of ions at selected activation energies and ion flux densities. Numerical calculation of the obtained expressions using the SRIM2000 software package showed that, at the selected ion flux density J, diffusion acceleration occurs only for processes with the activation energy exceeding a certain threshold value determined by the value of J, the type and energy of the ions.